US3681962A

US3681962A - Apparatus for rolling rings

Info

Publication number: US3681962A
Application number: US881114A
Authority: US
Inventors: Jacob Marcovitch
Original assignee: ROTARY PROFILE ANSTALT
Current assignee: ROTARY PROFILE ANSTALT
Priority date: 1969-12-01
Filing date: 1969-12-01
Publication date: 1972-08-08
Anticipated expiration: 1989-08-08

Abstract

This invention relates to rolling of annular workpieces by means of apparatus comprising a pressure roller, a mandrel which squeezes the workpiece against the pressure roller and backing rollers on which the mandrel rolls in line contact. Either the backing rollers or the pressure roller can be formed in two parts which can be adjusted towards and away from each other, either before or during rolling.

Description

United States Patent Marcovitch 1 Aug. 8, 1972 [541 APPARATUS FOR ROLLING RINGS [72] Inventor: Jacob Marcovitch, Johannesburg,

Republic of South Africa Assignee: Rotary Profile Anstalt, Vaduz,

Liechtenstein Filed: Dec. 1, 1969 Appl. No.: 881,114

Related US. Application Data Continuation-impart of Ser. No. 605,060, Dec. 27, 1966, abandoned.

[30] Foreign Application Priority Data Jan. 4, 1966 Republic of South J an. 10, 1966 Republic of South Africa ..66/ 105 Jan. 14,1966 Republic of South Africa .66/ 226 Feb. 7, 1966 Republic of South Africa ..66/ 684 Republic of South Africa ..66/261 1 Republic of South Africa ..66/865 Republic of South Africa ..66/225 Republic of South Africa ..66/477 May 5, 1966 Feb. 16,1966

Jan. 14, 1966 Jan. 27, 1966 Africa 66/43 April 12, 1966 Republic of South Primary Examiner-Milton S. Mehr Attorney-Young & Thompson ABSTRACT This invention relates to rolling of annular workpieces by means of apparatus comprising a pressure roller, a mandrel which squeezes the workpiece against the pressure roller and backing rollers on which the mandrel rolls in line contact. Either the backing rollers or the pressure roller can be formed in two parts which can be adjusted towards and away from each other, either before or during rolling.

11 Claims, 24 Drawing Figures memsnws 1912 3,681,962

SHEET 2 OF 7 Avwavrae (/6606 MmecaV/raw ,e r W PATENTEDAus 8 m2 3.681.962

sum 1 or 7 $4005 MAECOV/ 70H APPARATUS FOR ROLLING RINGS This application is a continuation-in-part of my copending US. Pat. application No. 605,060 filed Dec. 27, 1966 now abandoned.

This invention relates to the rolling of workpieces.

In my said co-pending application I have described the methods of rolling annular workpieces in which the axial width of the workpieces is controlled by means of grooves in a mandrel or a back-up member.

It is also known to roll rings using control rings into which the metal of the workpiece is forced. However, known methods of rolling in this way are not versatile and do not provide sufficient flexibility of operation, and suffer from a number of disadvantages which result mainly from the inability to apply sufficient pressure to the workpiece during rolling.

In both the methods as described in my said co-pending application and in the known art it is necessary to have special parts made i.e. either special mandrels or pressure rollers or alternatively a special control ring. While this may prove to be a satisfactory way of proceeding where large numbers of rings are to be rolled, it is not satisfactory when small batch production, i.e. of the order of, say, 20 rings, are being produced. When such small numbers of rings are being produced it has hitherto been necessary, according to my knowledge, to prepare these rings by forging.

It is an object of the invention to provide an effective and yet flexible means of rolling rings with the internal or the external diameter of the ring and the axial width accurately sized or wall thickness and axial width of the ring accurately sized.

Another object of the invention is to control the axial spread of the workpiece during rolling with good part definition independently of diametral spread. A further object of the invention is to provide apparatus for rolling rings of large diameter.

It is still a further object of the invention to provide apparatus for rolling rings of very large diameter and/or solid workpieces where very high pressures are to be applied to the workpiece.

SHORT DESCRIPTION OF DRAWINGS In the drawings:

FIG. 1 shows an arrangement of the invention using the two-roller system the section being taken on line 1-1 of FIG. 5,

FIG. 2 shows a modified arrangement of the invention using the two-roller system,

FIG. 3 is a section similar to FIG. 1 of a modified arrangement of the invention using the three-roller system,

FIG. 4 is a view of an arrangement of the invention shown in section, the section being taken on line 44 of FIG. 1

FIG. 5 is a similar section to other two-roller systems of the invention,

FIG. 6 is a section on line 6-6 of FIG. 5,

FIG. 7 is a section similar to FIG. 5 of another embodiment,

FIG. 8 shows a modified arrangement for rolling rings of large diameter,

FIG. 9 is a section similar to FIG. 4 of a further rolling system of the invention,

FIG. 10 is a similar view of a further embodiment,

FIGS. 11 and 12 are respectively a section and aside elevation of a further embodiment,

FIG. 13 is a'view similar to FIG. 12 of a further embodiment,

FIG. 14 is a cross-sectional view 'of a diametral cut through an annular workpiece, showing deformation of the workpiece under certain rolling conditions without side entrapment.

FIG. 15 is a similar view through a workpiece, showing a desired or preferred shape of the workpiece under ideal rolling conditions or with the embodiments of FIGS. 4 to 9 above.

FIG. 16 is a similar view through a workpiece, showing deformation under certain conditions which it is possible to achieve with the apparatus illustrated in FIGS. 17 to 24 below.

FIG. 17 is a semi-schematic end view of a further type of apparatus according to the invention for rolling an annular workpiece, shown at the start of rolling,

FIG. 18 is a partly sectioned side view of the apparatus of FIG. '17, certain parts being omitted for the sake of clarity,

FIG. 19 is a view similar to FIG. 17 of the same apparatus, near the end of rolling,

FIG. 20 is a view similar to that of FIG. 18, near the end of rolling and after re-positioning of the backing rollers,

FIG. 21 is a fragmentary side view of side rolling structure of the machine of FIGS. 17 to 20, the side rollers truing the ends of the workpiece,

FIG. 22 is a semi-schematic view of yet another embodiment in which there are double backing rollers,

FIG. 23 is a semi-schematic end view of yet a further embodiment, specifically for the manufacture of lorry wheels, with a hollow roller acting as a pressure body on the outer surface of the workpiece, and

FIG. 24 is a partly sectioned side view of the machine of FIG. 23.

GENERAL Referring now to the drawings, this invention is applicable to the two-roller system as shown in FIG. 1 or FIG. 2 or a three-roller system as shown in FIG. 3.

FIGS. 4 to 6 are described as if they are two-roller systems of the kind shown in FIG. 1, but it will be apparent that these arrangements can quite easily be modified so that they are equivalent to the two-roller system of FIG. 2 or the three-roller system of FIG. 3. Similarly the embodiments of FIGS. 7 and 8 are described as being two-roller systems as shown in FIG. 1 but with modifications which are obvious to those skilled in the art. These could be the two-roller" system of FIG. 2 or the three-roller system of FIG. 3.

FIG. 1.

FIG. 1 shows a two-roller system. By the term two-roller system as herein used is meant a system in which an annular workpiece 10 is rolled through the nip between pressure means in the form of a large convex pressure roller 12 and a mandrel 14, which mandrel is backed-up by back-up roller means 16. The back-up roller means 16 in the embodiments of the invention described with reference to FIGS. 4 to 6 comprise two axially aligned rollers as will be described in detail with reference to such figures. It will be seen that by provid ing the enlarged back-up means 12, large forces can be metal passing through the nip between the pressure roller 12 and the mandrel 14.

The rolling takes place by driving either the main pressure roller 12, which is the preferred arrangement, or the back-up means 16.

It will be seen that rolling of the workpiece takes place as the workpiece l and .the mandrel 14 passes between the'nip or the closest points of the pressure roller 12 and the backing means 16.

FIG. 2

The two-roller system of FIG. 2 is generally similar to that of FIG. 1. In this system again a workpiece is rolled between or through the nip between pressure means and a mandrel 14. The mandrel again being backed-up by back-up means 16. The

parts

10, 14 and 16 of the FIG. 2 embodiment are substantially identical to the

parts

10, 14 and 16 of the FIG. 1 embodiment. However, the pressure means in the FIG. 2 embodiment is the concave inner surface of an annular pressure roller 18. Because the workpiece 10 bears against the inner surface of the annular roller 18, there will be a larger area of contact between the outer surface of the workpiece 10 and the innersurface of the roller 18 than exists in the FIG. 1 arrangement where the pressure roller 12 is convex.

The same order of pressures can be applied with this arrangement and indeed perhaps slightly heavier pressures because of this larger support area of the pressure roller 18. v

It will also be noted that as the throat between the back-up means 16 and the annular pressure roller 18 is longer as compared to the system of FIG. 1, the workpiece 10 will be subjected to greater rolling reduction as it, the workpiece 10, and the mandrel 14 pass through this throat.

FIG. 3

FIG. 3 shows a three-roller system. Such a threeroller system comprises a convex main pressure roller 12, similar to pressure roller 12 of FIG. 1, and a mandrel 20 between the nip between which passes an annular workpiece 10. The mandrel 20 is substantially the same as the mandrel 14 of the FIGS. 1 and 2 embodiments save that it is provided a working portion 22 of a reduced diameter and two heads 24 at either end of this reduced portion. These heads 24 roll on a pair of backup means 26 and 28. Each of the back-up means may comprise a pair of back-up rollers similar to those described with reference to FIGS. 4 to 6. The main pressure roller 12 will be rotated or alternatively the backing roller means 26 and 28 may be rotated. It will be seen that with the three-roller system, as opposed to the two-roller system, the mandrel 20 can be held in position and rolling can take place as long as is desired. The mandrel can be a plain mandrel.

FIG. 4

In FIG. 4 the back-up means 16 is comprised by a pair of

cylindrical rollers

30 and 32. These

rollers

30 and 32 are co-axially arranged and have flat facing surfaces 34 and 36. The corners of which are radiused to prevent the edges of these

surfaces

34 and 36 respecworkpiece passes between these two surfaces. The

rollers

30 and 32 may be located at any desired distance apart to determine the axial width of the workpiece.

The

rollers

30 and 32 are movable toward and away from each other to vary this axial dimention of the workpiece 10. This movement which can be efiected by means of jacks as described with reference to FIG. 7, normally takes place before rolling commences. In this way the apparatus may easily be used for rolling small number of rings. The movement of the

rollers

30 and 32 axially inwardly and outwardly can also take place during the rolling operation. In this way better control of the metal flow during the rolling operation can take place.

It will also be noted that the rings will be rolled with substantially square sides. This means that an improved workpiece is provided.

It will also be noted that due to the difference in speeds between the

faces

34 and 36 of the rollers 30 these sides will be burnished by the

faces

34 and 36.

FIGS.5AND6 In the embodiments of FIGS. 5 and 6 back-up

rollers

38 and 40 are generally frusto-conical in shape and are provided with

conical faces

42 and 44 which are arranged so that the parts of the cone which are adjacent to the mandrel 14 are perpendicular thereto at the narrowest portion between these two

faces

42 and 44. This means that there will be curved faces bearing against the sides of the workpiece 10 as is more clearly shown in FIG. 6. In this way the amount of bumishing is held to a minimum and also the possibilities of the faces of the

backing rollers

38 and 40 scouring the sides of the workpiece is also kept to a minimum.

FIG. 7

The rollers 46 and 48 of the embodiment of FIG. 7 are generally similar to the frusto-

conical rollers

38 and 40 of the preceding embodiment. However, the rollers 46 and 48 are provided with

face members

50 and 51 respectively. These face

members

50 and 51 are double conical sided and are arranged in suitable recesses in the rollers. The

surface members

50 and 51 are arranged so that their facing surfaces are in the same relative position as the

surfaces

42 and 44 of the

rollers

38 and 40 of the FIG. 5 embodiment. Short stub axles 54 may be provided to rotate the

surface members

50 and 51 so that they approach more closely the peripheral speed of the workpiece 10. Alternatively the axles 54 may be idlers and serve merely to centralize the

surface members

50 and 51. In view of the high pressures that are going to be applied by the

surface members

50 and 51 on the workpiece 10, roller, taper roller or ball bearings 56 are provided between the

surface members

50 and 51 and the bases of the recesses in the rollers 46 and 48 respectively. This embodiment when of the three-roller system is the currently'preferred embodiment.

In FIG. 8 there is shown another apparatus of the invention. For convenience only half of the apparatus is shown in full, the other half of the apparatus is merely indicated by a chain dotted line.

In this apparatus there is provided backing rollers 58 which are provided with face members 60 that rotate relatively to the backing members on thrust rollers 62. The face members 60 each have a stub shaft 61 which is joumalled at 63 with the roller 58 to centralize the position of the face members 60. The stub shaft 61 passes only partially through the rollers 58. The backing rollers 58 are provided with stub axles 66 which are journalled at 68 in a right angled frame 70. This frame 70 is connected to a pair of hydraulic cylinders, not shown, by means of

piston rods

72 and 74 respectively. The entire apparatus is carried in a housing 76 having

openings

78 and 80 through which the

piston rods

72 and 74 respectively pass. The housing 76 has a pair of side cheeks 82 which serve as guide means 82 between which the inner frame 70 is slidable. The inner frame also carries a second frusto-conical roller 84 which has a stub-shaft 86 journalled in bearings 88 in the frame 70. This frustoconical roller 84 rolls on the outside surface of the face member 62 on the portion thereof diametrically opposite to the place where the roller 58 contacts the mandrel 14.

In this embodiment, the side faces of the workpiece roll against the faces of the conical member 84. Thus it will be appreciated that with this apparatus rings of greater inside and outside diameters can be rolled than is possible with the apparatus of FIGS. 4 to 7.

The backing rollers 59 are movable towards and away from the pressure rollers 12 by means of the hydraulic jack through the piston rod 74. Similarly these backing rollers are moved towards each other by the piston rod 72 of the other hydraulic jacks.

FIG. 9

In FIG. 9 there is provided the conventional mandrel 14 with two back-up rollers 168. The pressure means is however formed by two

pressure rollers

90 and 92. These

rollers

90 and 92 serve to define a workpiece 10A which is conveniently in the form of the inner race of a roller or taper roller bearing. The .pressure roller 90 is mainly frusto-conical. Its inside face is also frustoconical and it is arranged so that the portion of this conical face 94 is square to the axis of the mandrel 14. A short stub 96 is provided at the end of the conical face 94. The roller 92 is also basically frusto-conical in shape having two

rims

98 and 100 which define between them recesses 102 and 104 at each end of the rolling surface of the bearing race.

In this construction the

rollers

90 and 92 determine not only the width of the workpiece but also its profile and its thickness. The thickness is normally determined by the frusto-conical roller 90 coming into engagement with the mandrel 14 which thereby acts as'a stop. As the profile of the workpiece is mainly oblique and as it has re-entrant recesses, the roller 92 is moved inwardly relative to the roller 90 during rolling. This movement is indicated by the arrow 94 and is in a generally oblique direction, but with a component in the axial direction of the rollers. The roller is also moveable relative to the roller 92 so as to control the width of the shoulder 96A of the workpiece.

Here again the

rollers

90 and 92 may be set at a predetermined spacing before rolling but they may be movable as described above during rotation as described with reference to the preceding embodiments.

FIG. 10

In FIG. 10 the pressure means is comprised by two

annular rollers

98 and 100. A back-up shaft 102 passes freely through the rollers and serves as a common backing shaft for them. The shaft 102 has a cylindrical enlargement 104. The working

surfaces

106 and 108 of the rollers 98 and and the cylindrical surface of the enlargement 104 roll on the surface of the workpiece squeezing it, the workpiece, against the mandrel 14 in the same way as described above.

The position of the roller 98 is set by a shoulder 110 on the shaft 102 and also by the location of the enlargement 104. The position and axial movement of the roller 98 is set by a stop 112, the location of which may be adjusted but is set before each rolling operation.

The enlargement 104 may be omitted in which case the

rollers

98 and 100 alone will determine the profile of the workpiece.

GENERAL (AS TO THE PRECEDING FIGURES) In all the embodiments described above the rolling of the workpiece can be effected hot, warm or cold. The rollers which move together may do so under high pressure which may be of the order of one hundred tons per square inch.

In a particular embodiment in which a mild steel workpiece has an initial outside diameter of 6 in. and inner diameter of 5 in. and a width of if; in., the ring could be rolled in a few seconds to half its wallthickness in the cold in apparatus of FIGS. 5 and 6 with the three roller system.

All the embodiments enable one to roll rings with a high degree of finish and with square parallel sides in a single operation. It will be appreciated that with this invention a ring having two of the three dimensions mentioned above may be accurately rolled, the degree of consistency of the third dimension depends upon the consistency of the original blanks.

It will also be understood that the rolling may be carried out in stages if the diameter of the openingin the workpiece is very small so that initially one would roll with a mandrel of small diameter and as the diameter of the hole increases a larger mandrel may be used so that greater feeds and pressures may be applied to the workpiece. It will be further understood that the pressure means and the mandrels in all the embodiments may be profiled so as to roll profiled rings.

The apparatus above described are particularly versatile and hence useful for a jobbing shop in which small numbers (say 20) of accurately rolled rings of any one set of dimensions are rolled. The apparatus can be for rolling greater or lesser numbers of rings.

It will be understood that if the backing rollers 16 are moved towards each other during rolling it will normally be necessary to back off the pressure roller relative to the mandrel to allow for a growth in the wall thickness of the workpiece.

It will also be noted that in all the preceding embodi ments of the invention the movement of the rollers (e.g. 30 and 32; 38 and 40; 90 and 92 etc) relative to each other is independant of relative movement between the mandrel and the pressure means.

FIGS. 11 AND 12 In FIGS. 11 and 12 the pressure means comprises a roller 114. There are a pair of

identical backing rollers

117, 118 mounted side by side on

stub axles

120 and 122 and spaced apart to provide a gap 119 between them. The

axles

120 and 121 are journalled in bearings 122 in bosses'123 provided by the frame 124 of the machine on either side of the gap 119. An annular workpiece 125 extends within the gap 1 19 and its cavity contains a mandrel 126. The mandrel 126 projects to each side of the workpiece 125 and is formed with heads 127 that roll on the rollers 117,118. The workpiece is surrounded by a control ring 128 that limits its diametral spread.

If it should be necessary, back-up rollers 129 are provided which bear against the

rollers

117, 118. The back-up rollers 123 may also be arranged in pairs spaced apart to allow very large workpieces 125 to extend through the gap 119 between them. 'It is pointed out that the provision of back-up rollers 129 pemiits the

rollers

117, 118 to be loose in the sense that they need not be confined in bearings. They can, therefore, be quickly removed and replaced.

The

rollers

117, 118 may be spaced apart variably in order to accommodate workpieces of different thicknesses.

The diameter of rings which may be profiled in the machine is limited only by the amount of space available around the machine.

FIG. l3

In FIG. 13, the three-roller system consists of the

rollers

130, 131 and 132. The mandrel 133 rolls on the

rollers

131, 132 and the workpiece-134 is pressed by the mandrel against the periphery of the roller 130. The

rollers

131, 132 are paired and mounted on stub axles, like the

rollers

117, 118 of FIG. 11. The workpiece extends through the gap between the pairs of

rollers

131, 132.

The

rollers

131, 132 may be backed up by rollers 135, which may also be paired to allow very large workpieces to be handled.

It is pointed out that the larger the diameter of the workpiece, and the larger the deformation required, the longer the time in, and the greater the number of passes through, the throat, so that the entire circumference of the workpiece is rolled.

FIG. 14

FIG. 14 illustrates a known condition in ring-rolling according to the prior art. It will be noticed that the workpiece 10.1 has concave ends. This situation arises from rolling the workpiece between an inner and an outer pressure body, such as a pair of rollers, (not illustrated) under weak feed conditions; that is, under conditions where the inner and outer rollers are pressed relatively lightly towards each other as they are rotated,

to advance the workpiece circumference progressively through the space between them. With such rolling, normally done hot, the workpiece tends to expand diametrically and also axially. If the axial expansion leads to excessive concavity at the ends of the article, the article will clearly be defective, and rolling will tend to break down before the wall thickness of the workpiece has been reduced to the maximum extent that may be desired.

FIG. 15

In FIG. 15, the workpiece 10.2 is seen to have substantially square ends. This situation will usually be ideal if considerable thinning and axial elongation is required. However it may be unobtainable on a reproducible basis except when means are provided to define the sides of the workpiece as indicated in FIGS.

.4 to 9 described above.

FIG. l6

FIGS. 17TO 20 In FIGS. 17 to 20, a three-roller machine for producing plain cylindrical articles is illustrated. It

comprises basically a mandrel 14, back-up means comprising centilevered backing rollers 16, pressure means comprising a pressure roller 12, and side rollers 218. The mandrel 14 is, in the drawings, a plain cylinder, but mandrels with profiled surfaces may also be used, with due allowance for their individual profiles.

The ends of the mandrel 14 are supported on the backing rollers 16, which in turn are set in bearings 224 in a stout framework or other structure 222. The parts framework 222 on each side of the workpiece 220 is relatively movable, as indicated-by the arrows 250 in FIGS. 18 and 20 by means of hydraulic jacks or the like 1 (not shown). The ends of the backing rollers 14 are, as

seen in FIG. 18, separated from each other by a space 230 into which the workpiece 220 extends, and which is axially longer than the axial length of the workpiece 220. As seen in FIG. 17, the inner diameter of the workpiece 220, at the start of the operation is too small to accommodate the ends of the backing rollers 16 and the mandrel 14; hence separated rollers 16 are provided to form the gap 230. In practice, it may be preferable to provide interengaging means in the form of a spigot 232 on one of the rollers 16 to interlock with a socket 234 on an axially aligned backing roller at the other end of the workpiece. In this way the rigidity of the backing for the mandrel 12 may be enhanced, allowing it to take a greater load and so improving the capacity of the machine. However the provision of these interengaging means is not always essential.

The pressure roller 12, bearing on the outer surface of the workpiece 220, is supported on a shaft 236 in bearings 38, the shaft 36 being fixed in robust framework structure 240 (FIG. 18). These parts are shown to small scale in the drawings for clarity. The structure 240 is movable relatively towards and away from the axes of the backing rollers 16 and mandrel 14, also by hydraulic jacks or the like (not shown).

The ends of the workpiece 220 are trued by a series of side rollers 218, mounted to bear on the workpiece ends at points spaced about their circumference. The rollers 218 yield to permit axial expansion of the workpiece while simultaneously truing its ends. As seen in FIG. 21, they may be mounted on yokes 244 that are governed by hydraulic or other pressure means (not shown) through arms 246.

When a blank workpiece 220 is to be loaded into the machine, the framework members 222 on each side of the machine are drawn apart as shown by the arrows 250 to withdraw the spigots 232 on the rollers 14 from the sockets 234 in the opposite rollers 14. The workpiece 220 is then threaded on to the backing rollers 16. The mandrel 14 is placed in position, and the framework members 222 are advanced until the ends of the mandrel 14 are supported by the rollers 16. In this position the rollers 16 do not extend into the hollow of the workpiece, except as regards the spigot 232. To complete loading of the machine and bring it to the condition shown in FIGS. 17 and 18, the pressure roller 12 is brought into contact with the outer surface of the workpiece 220.

Rolling then begins. The pressure roller 12 is rotatably driven (by any conventional means not illustrated) to impose rotation frictionally on the workpiece 220, the mandrel 14, and the backing rollers 16. If need be some of the rotary members other than the pressure roller 12 may be driven to attain the correct conditions. This rotation advances the workpiece circumference progressively through the nip or space between the mandrel 14 and the pressure roller 12. By applying a suitable feed between the pressure roller 12 and the backing rollers 16, (eg by the means which move the structure 240), the workpiece 220 is deformed under pressure to cause it to expand diametrically. Axial expansion is regulated to a required factor by the side rollers 218.

After a measure of deformation, the workpiece diameter has increased to the point where the inner diameter clears the ends of the backing rollers 16, viewed from the end. At this stage rolling is halted. The force urging the pressure roller 12 towards the backing rollers 16 is slackened, now the framework members are moved in the direction of the arrows 250, so that the spigots 232 are forces fully into the sockets 234 and the inner faces of the rollers 16 butt against each other to make the rollers 16 extend effectively continuously through the workpiece aperture. Alternatively a mandrel of larger diameter can be substituted for the mandrel originally used. The biggest mandrel possible should be used at each stage if one desires maximum feed and hence more working throughout the depth of the ring wall. In this condition, seen in FIGS. 19 and 20 the mandrel 14 is supported along its full length and not only at its ends. Rolling can then be resumed at very large feed forces since with the improved backing for the mandrel 14, these forces can be accommodated by the machine without undue stress. Since at this stage the workpiece 220 is thinner than before and offers greater resistance to deformation, the gain in feed force capacity is extremely useful.

It is obvious that the ends of the workpiece can be constrained by the side rollers 218 throughout the operation, to prevent raggedness or irregularity at these ends, leading to the production of a well finished article at the end of the operation.

The unloading procedure is simple, the pressure roller 12 being withdrawn and the backing rollers 16 being drawn apart to allow the workpiece to be freed and removed from the machine with the mandrel.

.FIG. 22

FIG. 22 illustrates a development of the invention in which there are two pairs of backing rollers 16 to support the mandrel. As in the machine of preceding FIGS. 17 to 21, there is a pressure roller 12, a mandrel 14, a series of side rollers 218, and a pair of backing rollers 16 on which each end of the mandrel 14 rolls. In addition, a pair of secondary backing rollers 260 at each end on which the backing rollers 16 in turn are supported. The structure holding these components in position and driving the machine is not illustrated.

The workpiece 250 is shown in solid lines in its ex-. panded state and in its initial state is shown in chain lines at 250A. It is obvious that the workpiece 250A cannot accommodate within its aperture the mandrel l4 and the

double backing rollers

16 and 260. Thus the operation starts with the

rollers

16 and 260 axially separated at the ends of the mandrel. The

rollers

16 and 20 are brought into axial abutment when the workpiece has expanded to the diameter shown by 250. If desired, the rollers 16 can be moved into abutment as soon as they can be accommodated in the workpiece.

FIGS. 23 AND 24 Another development is shown in FIGS. 23 and 24. Here there is again a mandrel 14B, backing rollers 16 with (if desired) spigot connections 132 and 234 (see FIG. 24), an annular workpiece 270 and a pressure means. In this case pressure means comprises a hollow roller 272. The interior concave surface 274 of roller 272 bears on the outer surface of the workpiece 270. The roller 272 is set in bearings 276 in framework structure 278. The mandrel 148 has a tapered end 280 that, as seen in FIG. 24, provides a taper on the finished workpiece 270, which in this case is a lorry wheel. Side rollers 282 roll the end zone of the workpiece 270 into a flange 284, the pressure roller 272 being rebated to accommodate the flange 284.

With the machine of FIGS. 23 and 24, the workpiece 270 is initially inserted into the hollow of the roller 272 with the mandrel 14B threaded through it, and the backing rollers 16 are closed up axially to allow the ends of the mandrel to roll on the rollers. The backing rollers 16 are themselves located axially beyond the ends of the workpiece. When rolling has advanced sufficiently, the backing rollers 16 are brought axially together within the workpiece aperture to attain the situation shown in FIG. 24, so providing support for the mandrel 14B continuously along its length.

required value. The finished workpiece 270 is removedfrom the roller 272 by suitable ejection means (not illustrated).

A loose control ring for this purpose might be used with the machines described earlier.

In this embodiment, as in the embodiment of FIGS. 17 to 21, the rolling of the workpiece can be effected hot, cold or warm. The pressures in this embodiment may be of the same order as in the preceding embodiment.

Iclaim:

1. In apparatus for rolling rings from annular workpieces comprising main pressure means and .a onepiece mandrel which in use are urged towards each other to squeeze a workpiece therebetween and the apparatus further comprising back-up means on which at least part of the mandrel rolls;.the improvement that the back-up meanscomprises at leastv one set of two rollers which are axially spaced apart and are disposed on and contact the side of the mandrel opposite the main pressure means. I

2. The invention as claimed in claim 1 further comprising movable means operatively connected to at least one of the rollers to move them to adjust the axial spacing between the rollers during operation of the apparatus.

3. The invention as claimed in claim 2 in which the movement of the said rollers is independent of the in use contacts the sides of a workpiece being rolled in the apparatus.

6. The improvement as claimed in claim 5 wherein the conical front portion is rotatable relative to the said frusto-conical portion of the roller.

. 7. The invention as claimed in claim 6 further comprising axle means attached tothe said conical front portion and passing at least partially through the said frusto-conical portion of the roller.

8. The improvement as claimed in claim 5 further comprising an additional conical roller rolling on the front portion of each roller and in use contacting the sides of a workpiece being rolled in the apparatus.

9. The invention of claim '1 comprising slidable interengaging means connecting the rollers.

10. The invention as claimed in claim 9 in which the interengaging means comprises a stub shaft on one of the rollers and a socket in said interengaging means, which socket slidably receives the said stub shaft.

11. The invention as claimed in claim 1, wherein the axial spacing between the rollers is adjustable.

Claims

1. In apparatus for rolling rings from annular workpieces comprising main pressure means and a one-piece mandrel which in use are urged towards each other to squeeze a workpiece therebetween and the apparatus further comprising back-up means on which at least part of the mandrel rolls; the improvement that the back-up means comprises at least one set of two rollers which are axially spaced apart and are disposed on and contact the side of the mandrel opposite the main pressure means.

3. The invention as claimed in claim 2 in which the movement of the said rollers is independent of the movement of the pressure means towards the mandrel.

4. The invention as claimed in claim 1 in which the back-up means comprises two sets of rollers on which the mandrel rolls, the axial spacing between the rollers of each set being adjustable.

5. The improvement as claimed in claim 1 in which each of the said rollers has a frusto-conical portion on which the mandrel rolls and a conical front portion that in use contacts the sides of a workpiece being rolled in the apparatus.

7. The invention as claimed in claim 6 further comprising axle means attached to the said conical front portion and passing at least partially through the said frusto-conical portion of the roller.

9. The invention of claim 1 comprising slidable interengaging means connecting the rollers.